1. Field of the Invention
The present invention relates in general to a wheel cover detachably attached to a road wheel, and more particularly, to a plastic wheel cover designed to be detachably retained on a monolithic wheel disc, such as aluminium wheel dics and the like. More specifically, the present invention is concerned with a retaining arrangement which is designed to facilitate the retaining of the wheel cover to the wheel disc.
2. Description of the Prior Art
In order to clarify the task of the present invention, one of conventional plastic wheel covers will be outlined with reference to FIGS. 9 and 10 of the accompanying drawings, which is disclosed in Japanese Utility Model First Provisional Publication No. 60-148101.
Referring to the drawings, there is shown a conventional plastic wheel cover 3 which is designed to be detachably retained on an aluminium wheel disc 1. The wheel disc 1 is formed with a concentric circular recess (no numeral) which faces outward. A concentric annular ridge 2 is integrally formed on a side wall of the circular recess, which is raised radially inwardly as shown. Designated by numeral 2a is a top of the annular ridge 2, and 2b is an outside surface of the annular ridge 2.
The plastic wheel cover 3 has a series of lugs 4 molded integrally therewith on the inboard face of the cover 3. The lugs 4 are spaced equally around the circumference of the cover 3 and have respective latching pawls (no numerals) at the leading ends. Each lug 4 has a reinforcing rib (no numeral) integrated therewith. The wheel cover 3 has further a series of stoppers 5 integrated therewith. The stoppers 5 are arranged to alternate with the lugs 4. The lugs 4 are biased radially outwardly by a resilient wire ring 6 which is held by the lugs 4.
Upon requirement of retaining the wheel cover 3 to the wheel disc 1, the wheel cover 3 is brought to a proper temporary position as is shown in FIG. 9 wherein some of the latching pawls of the lugs 4 contact with the top 2a of the annular ridge 2 and some of the stoppers 5, which are arranged at diametrically opposite positions of the lugs 4, contact with the outside surface 2b of the ridge 2. Then, the wheel cover 3 is forced flatwise against the outer face of the wheel disc 1. Usually, the wheel cover 3 is strongly pushed or struck with a heel of an operator's hand. With this, the latching pawls 4 of all lugs 4 are brought into a latching engagement with the annular ridge 2 in a snap action manner against the force of the wire spring 6. Excessive insertion of the wheel cover 3 to the wheel disc 1 is suppressed by the stoppers 5 which are now in contact with the outside surface 2b of the annular ridge 2.
However, due to its inherent construction, the above-mentioned conventional wheel cover 3 has the following drawback.
That is, as is shown in FIG. 10, upon bringing the wheel cover 3 to the temporary position, it sometimes happens that some of the stoppers 5 are deeply engaged with the top 2a of the annular ridge 2 causing the latching pawls of the diametrically opposite lugs 4 to abut against the outside surface 2b of the annular ridge 2. If, under this condition, the wheel cover 3 is strongly pushed or struck, the lugs 4 and the stoppers 5 may be damaged or broken. In fact, because the wheel cover 3 assuming this inproper temporary position is viewed very similar to that assuming the above-mentioned proper temporary position, the undesired pushing and striking against the wheel cover 3 has been carried out very often.